/*****************************************************************************
The Dark Mod GPL Source Code

This file is part of the The Dark Mod Source Code, originally based
on the Doom 3 GPL Source Code as published in 2011.

The Dark Mod Source Code is free software: you can redistribute it
and/or modify it under the terms of the GNU General Public License as
published by the Free Software Foundation, either version 3 of the License,
or (at your option) any later version. For details, see LICENSE.TXT.

Project: The Dark Mod (http://www.thedarkmod.com/)

******************************************************************************/

#ifndef _DOWNLOAD_H_
#define _DOWNLOAD_H_

#include "../Http/HttpRequest.h"
#include <thread>

/**
 * An object representing a single download.
 * The actual work will be performed in a separate thread,
 * hence the Start() method will not block execution.
 *
 * Check the GetStatus() and GetProgressFraction() methods
 * to get some information about the actual status.
 * 
 * Once the Download object is destroyed any ongoing 
 * worker thread will be terminated.
 *
 * Download data is stored in a temporary file until the whole
 * file is finished - then the temporary will be renamed to
 * the destination filename. If the destination filename is already
 * in use, the move will fail and the download will remain
 * in the temporary file. The temporary file is named the same
 * as the destination filename, but with a prefixed underscore character:
 * e.g. target/directory/_download.pk4
 */
class CDownload
{
private:
	// The target URLs we're trying to download from
	idStringList _urls;

	// The URL index
	int _curUrl;

	// destination file
	idStr _destFilename;

	// Temporary filename for partial download data
	idStr _tempFilename;

public:
	enum DownloadStatus
	{
		NOT_STARTED_YET,
		IN_PROGRESS,
		FAILED,
		SUCCESS,
		CANCELED,//Agent Jones
		MALFORMED,	//stgatilov: checksum invalid
	};

	// Some additional data which can be set by clients
	struct UserData
	{
		int		id;		// an arbitrary ID, -1 by default
		int		id2;	// an arbitrary ID, -1 by default
		void*	ptr;	// a pointer, NULL by default

		UserData() :
			id(-1),
			id2(-1),
			ptr(NULL)
		{}
	};

private:
	DownloadStatus _status;

	// The corresponding HTTP request
	CHttpRequestPtr _request;

	typedef std::shared_ptr<std::thread> ThreadPtr;
	ThreadPtr _thread;

	bool _pk4CheckEnabled;
	idStr _expectedSha256;	//empty if check is ignored

	UserData _userData;

	// The ID of the related download (mission + l10n)
	int	_relatedDownload;

public:
	/**
	 * greebo: Construct a new Download using the given list of 
	 * alternative URLs. If downloading from the first URL fails
	 * the next one will be tried until no more alternatives are left.
	 * The result will be saved to destFilename.
	 */
	CDownload(const idStringList& urls, const idStr& destFilename, bool enablePK4check = false);

	~CDownload();

	// stgatilov: sha256 must be valid 64-digit hex number or empty string.
	// If empty, then sha256 check is disabled (default).
	// If not empty, then sha256 checksum of downloaded file will be computed and verified after download.
	void VerifySha256Checksum(const idStr &sha256);

	// Start the download. This will spawn a new thread and execution
	// will return to the calling code.
	void Start();

	// Cancel the download. If the download has already finished, this does nothing.
	void Stop(bool canceled);

	// Enable the validation of the downloaded file
	void EnableValidPK4Check(bool enable);
	
	// The current status of this download
	DownloadStatus GetStatus();

	double GetProgressFraction();

	// Get the ID if the related download (e.g. a mission might have a l10n pack as related download)
	int GetRelatedDownloadId();

	void SetRelatedDownloadId(int relatedDownloadId);

	// UserData accessors
	const UserData& GetUserData() const { return _userData; };
	UserData& GetUserData() { return _userData; };

	// Get path to file where downloaded data is saved
	const char *GetDestinationFilename() const { return _destFilename.c_str(); }

	// Check method
	static bool CheckValidPK4(const idStr& path);

private:
	// Thread entry point
	void Perform();
};
typedef std::shared_ptr<CDownload> CDownloadPtr;

#endif /* _DOWNLOAD_H_ */